I found this at the back of a copy of the Epitome Sacrae Historiae. There was an institute called Dr. Comstock's Vocal and Polyglott Gymnasium in Philadelphia. According to this institute: t"he Ancient Greek is taught according to the system adopted in the University of Otho, at Athens. By this method both the ancient and modern dialects are acquired at the same time. This plan is now used in the Universities of Germany." Would anyone happen to know what such a curriculum looked like? It sounds pretty intriguing to me.

The katharevousa is not so far from the classical idiom as the current demotiki is. It might be plausible to learn those two together.

Thou wast not born for death, immortal Bird!
No hungry generations tread thee down;
The voice I hear this passing night was heard
In ancient days by emperor and clown:
(Keats, Ode to a nightingale, 1819).

Although Katharevousa was officially removed from the Greek educational system in 1976, it would have been going strong back in Comstock's day, and as ἑκηβόλος points out, there are many similarities with Attic Greek. It does not have the complexity of ancient Greek, but many of the forms and inflections as well as vocabulary are restored. Katharevousa (meaning "purified") was an attempt to remove the influence of foreign languages (such as Turkish, Italian, French) on the popular language (demotic greek). Its use, however, was restricted to official documents, newspapers, textbooks and other forms of written communication. The only place it was spoken was in the courtroom!